That's not an AppData folder like on windows, it's a user home directory for Godot, the game engine Strive uses. I wrote that path based upon what the game code does to get the path and this: https://godotengine.org/qa/12630/where-does-user-point-to-in-different-os which says on Mac OSX the path is ~/.godot/app_userdata/yourgame so ~/.godot/app_userdata/strive/mods would be the mod path.
The mods folder won't exist yet, and the parent folder won't necessarily already exist either. You have to create this path.
However, the way the game works makes it likely mods won't work on Mac because they're bindled into the "app" and thus it might lack permissions it expects to manipulate data within the app as OSX wants the app to be doing that outside of it's .app structure.